Double U design for mid-turbine frame struts

Abstract

A mid-turbine frame is connected to at least one mount of a gas turbine engine for transferring a first load from a first bearing and a second load from a second bearing to the mount. The mid-turbine frame includes a first load structure, a second load structure, and a plurality of struts. The first load structure combines the first load and the second load into a combined load. The second load structure transfers the combined load to the mount. The struts are connected between the first load structure and the second load structure and transfers the combined load from the first load structure to the second load structure.

1. A mid-turbine frame connected to at least one mount of a gas turbine engine for transferring a first load from a first bearing and a second load from a second bearing to the mount, the mid-turbine frame comprising:
 a first U-shaped load structure for combining the first load and the second load into a combined load; 
 a second load structure for transferring the combined load to the mount; 
 a plurality of struts connected between the first load structure and the second load structure for transferring the combined load from the first load structure to the second load structure. 
 
   
   
     2. The mid-turbine frame of  claim 1 , wherein the second load structure is U-shaped. 
   
   
     3. The mid-turbine frame of  claim 1 , wherein the first load is transferred to the mid-turbine frame through a first bearing cone and the second load is transferred to the mid-turbine frame through a second bearing cone. 
   
   
     4. The mid-turbine frame of  claim 1 , wherein the plurality of struts are tilted with respect to the first load structure and the second load structure. 
   
   
     5. The mid-turbine frame of  claim 1 , wherein the plurality of struts are perpendicular with respect to the first load structure and the second load structure. 
   
   
     6. The mid-turbine frame of  claim 1 , wherein the first load structure comprises:
 a stem for combining the first and second loads into the combined load; 
 a branch connected to the stem for absorbing a portion of the combined load from the stem; and 
 a first torque box having a first end and a second end, wherein the first end of the first torque box is connected to the stem and the branch, and wherein the second end of the first torque box is connected to the plurality of struts. 
 
   
   
     7. The mid-turbine frame of  claim 6 , wherein the first torque box transfers the combined load from the stem and the branch to the plurality of struts. 
   
   
     8. The mid-turbine frame of  claim 1 , wherein the second load structure comprises a second torque box for accepting the combined load from the plurality of struts, wherein the second torque box has a first end connected to the plurality of struts and a second end connected to the mount. 
   
   
     9. A mid-turbine frame having multidirectional load transfer for transferring a first load and a second load to an engine casing, the mid-turbine frame comprising:
 a first U-shaped stiffening structure for combining the first load and the second load; 
 at least one second stiffening structure for transferring the combined load to the engine casing; and 
 a plurality of struts connecting the first stiffening structure to the second stiffening structure. 
 
   
   
     10. The mid-turbine frame of  claim 9 , wherein the second stiffening structure is U-shaped. 
   
   
     11. The mid-turbine frame of  claim 9 , and further comprising a plurality of second stiffening structures. 
   
   
     12. The mid-turbine frame of  claim 9 , wherein the first stiffening structure is a first torque box having a ring structure. 
   
   
     13. The mid-turbine frame of  claim 9 , wherein the second stiffening structure is a second torque box. 
   
   
     14. A lightweight mid-turbine frame for combining and transferring a first load and a second load from a first bearing and a second bearing, respectively, to an engine casing housing the mid-turbine engine, the mid-turbine engine comprising:
 a first U-shaped torque box for combining and absorbing the first and second loads; 
 at least one strut having a first end and a second end, wherein the first end of the strut is connected to the first torque box, and wherein the strut carries the load from the first end of the strut to the second end of the strut; and 
 a second torque box connected to the second end of the strut for transferring the load to the engine casing. 
 
   
   
     15. The mid-turbine frame of  claim 14 , wherein the strut is positioned orthogonally with respect to the first torque box and the second torque box. 
   
   
     16. The mid-turbine frame of  claim 14 , wherein the strut is tilted with respect to the first torque box and the second torque box. 
   
   
     17. The mid-turbine frame of  claim 14 , wherein the second torque box is U-shaped.